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UNITED STATES PATENT OFFICE.

JUAN S. L. BABBS, OF BOSTON, MASSACHUSETTS, AND AMOS H. RAY, OFPROVIDENCE, RHODE ISLAND.

ADJUSTABLE GAGE FOR DOVETAILS.

Specication of Letters Patent No.

To all whom it may concern.'

Be it known that we, JUAN S. L. BABBs, of Boston, in the county ofSuffolk and Commonwealth of Massachusetts, and AMos H. RAY, of the cityand county of Providence and State of Rhode Island, have invented a newand useful Graduating Dovetail Gage, for Marking or Setting OutDovetails on Wood Preparatory to Sawing; and we do hereby declare thatthe following is a. full, clear, and eXact description thereof,references being had to the annexed drawings, which form a part of thisspecification.

Hitherto no instrument has been invented, as your petitioners verilybelieve, which can be employed advantageously for marking dovetails.

This new invention obviates all former objections to the old method ofsetting out dovetails by hand (in a manner hereinafter described) Figure1, is an elevation of the graduating dovetail gage. Fig. Q, is a plan ofthe same. Fig. 3 is a transverse section.

A, A, is the bar, being a straightI piece of wood having a series ofcutter heads marked C, C, with knives or markers, attached to` the top,and bottom sides of the same. The cut-ter heads are made to slide easilyupon the bar, and are held in their respective places by set-screws d,(Z, thereby admitting of adjustment for marking various sizes ofdovetails, as may be required.

B, B, are movable or sliding gages, and are also made to slide upon thebar A, A, in the same manner as the cutter heads before described. Thesegages are provided with elongated slots, which allows them to traversebackward and forward upon the bar A, A, at right angles with the same,by which means this instrument may be used for marking the dovetailsupon one piece of stock, and also the pins upon the other piece, tomatch the dovetails, by employing but one set of the knives or markers.

f, f, are stops, for the movable gages B, B, when used upon variousthickness of stock, by changing the position of these stops and movingthem nearer or farther from the center of the elongated slots; thelength of the dovetails may be increased or diminished. These stops mayalso be formed by inserting a screw at the end of each of the gages ofsuicient length to admit of the graduation required.

18,838, dated December 15, 1857.

D, is the end guide, and is designed to govern the first dovetail fromthe edge of the stock. This consists of a head, similar to the commongage head, and is also made to slide upon the bar, to accommodate thedifferent widths of stock to be marked.

e, c, are plain heads, and are used to hold the sliding gages in theirproper places; the sliding gages being placed upon the bar outside oft-he end cutter head, the plain head is then placed against the same,thus allowing the gage to traverse freely between them.

Mode of using: 1st, place the cutters upon the end of the piece to bemarked, having the end piece D, in the left hand, carry the instrumentfrom you, until the movable gages are checked by the stops f, f. Move itto the right until the end guide D strikes against the edge of theboa-rd; then place a block of wood upon the top cutters and give thesame a slight blow with a mallet or some like instrument, and a perfectimpression is obtained. After marking the dovetails and pins, upon oneend of the stock, turn the instrument over, holding the end piece D, inthe right hand, and proceed as before upon the other end of the stock,the result will be the same.

By the use of an instrument so construct-- ed much time and labor issaved, as also a greater uniformity is obtained. Numbering each piece ofstock 1, 2, 3, &c., as in the old method of setting out dovetails byhand is rendered unnecessary, as the workman can depend upon any numberof pieces marked with this instrument fitting together perfectly.

Having thus described our invention, we will state our claims:

1. The use of the bar A, A, provided with two or more stationary, ormovable, cutterheads, with knives or markers attached, as described, forthe purpose herein set forth.

2. The arrangement of the movable gages B, B, operating as described,for the purpose specified.

JUAN S. L. BABBS. AMOS H. RAY.

Witnesses:

JAMES M. MOORE, WM. H. WHITAKER.

